Recent studies have identified the presence of familial clustering of ischemic sudden cardiac death (SCD) as a clinical expression of coronary artery disease. The purpose of this study was to determine whether nonischemic SCD has a similar familial background, which would be evidence of a genetic predisposition.
The retrospective case-control study included (1) consecutive victims of nonischemic SCD (n=223), (2) consecutive victims of ischemic SCD (n=596), whose deaths and diagnosis were verified at medicolegal autopsy, and (3) control subjects without heart disease (n=475). In each study group, the family history of SCD among the first-degree relatives was determined and verified from death certificates. The prevalence of SCD in =1 first-degree relative was significantly higher in victims of ischemic (34.2%) than nonischemic SCD (13.4%; P